The use of higher communication frequencies in recent years has brought ongoing commercialization of highly directional communication between mobile devices such as portable information terminals. A problem with such communication is interruption of communication due to slight changes in the positions or angles of the mobile devices.
Meanwhile, the miniaturization of gyro sensors has led to gyro sensors beginning to be installed in mobile devices. Correcting the direction of directivity based on a displacement amount of a mobile device acquired by a gyro sensor installed in that mobile device enables more stable and optimal communication to be implemented than with conventional mobile devices.
An antenna control apparatus disclosed in Patent Document 1 is known as such a technology, for example. The antenna control apparatus disclosed in Patent Document performs high-precision satellite supplementation by means of an antenna installed in a vehicle. Specifically, this apparatus uses a means of detecting GPS information and yaw angle (azimuth angle) information and an inclinometer that detects the angle of inclination of the vehicle to perform high-precision drive control of the azimuth angle and elevation angle directions of the antenna.
An antenna control apparatus disclosed in Patent Document 2 is also known, for example. The antenna control apparatus disclosed in Patent Document 2 has a gyro, a movement amount sensor, and a radio field intensity detection and evaluation section. The gyro detects the orientation of the apparatus. The movement amount sensor detects an amount of movement of the apparatus. The radio field intensity detection and evaluation section determines whether or not a radio wave received from another apparatus that is a communicating party is greater than or equal to a predetermined threshold value. The antenna control apparatus of Patent Document 2 performs a direction scan in order to identify the direction in which the other apparatus is located. Then, if the radio field intensity detection and evaluation section outputs an indication that a radio wave from the other apparatus is greater than or equal to the threshold value after performing a direction scan twice, this apparatus decides the orientation of the directional antenna based only on the output of the gyro and the movement amount sensor—that is, without performing a direction scan.    Patent Document 1: Japanese Patent Application Publication No. HEI 7-118607    Patent Document 2: Japanese Patent Application Laid-Open No. 2006-211154